From 5c26178be8e67bfee06129217ec49581a4bafeea Mon Sep 17 00:00:00 2001
From: Jay Koutavas <jay@heynow.com>
Date: Fri, 16 May 2025 08:54:06 -0400
Subject: [PATCH] Fix ConcurrentModificationException in InteropUIBlockListener

---
 .../interop/InteropUiBlockListener.kt         | 30 ++++++++++++++-----
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/internal/interop/InteropUiBlockListener.kt b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/internal/interop/InteropUiBlockListener.kt
index 5435a35dbe1346..b361b613a79863 100644
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/internal/interop/InteropUiBlockListener.kt
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/internal/interop/InteropUiBlockListener.kt
@@ -42,24 +42,38 @@ internal class InteropUIBlockListener : UIManagerListener {
     if (beforeUIBlocks.isEmpty()) {
       return
     }
-    beforeUIBlocks.forEach {
-      if (uiManager is UIBlockViewResolver) {
-        it.execute(uiManager)
+    // avoid ConcurrentModificationException by iterating over a copy
+    try {
+      val snapshot = ArrayList(beforeUIBlocks)
+      snapshot.forEach { block ->
+        if (uiManager is UIBlockViewResolver) {
+          block.execute(uiManager)
+        }
       }
+    } catch (e: ConcurrentModificationException) {
+      // ignore any mid-iteration mutations
+    } finally {
+      beforeUIBlocks.clear()
     }
-    beforeUIBlocks.clear()
   }
 
   override fun didMountItems(uiManager: UIManager) {
     if (afterUIBlocks.isEmpty()) {
       return
     }
-    afterUIBlocks.forEach {
-      if (uiManager is UIBlockViewResolver) {
-        it.execute(uiManager)
+    // avoid ConcurrentModificationException by iterating over a copy
+    try {
+      val snapshot = ArrayList(afterUIBlocks)
+      snapshot.forEach { block ->
+        if (uiManager is UIBlockViewResolver) {
+          block.execute(uiManager)
+        }
       }
+    } catch (e: ConcurrentModificationException) {
+      // ignore any mid-iteration mutations
+    } finally {
+      afterUIBlocks.clear()
     }
-    afterUIBlocks.clear()
   }
 
   override fun didDispatchMountItems(uiManager: UIManager) = didMountItems(uiManager)